28129638 has 8 divisors (see below), whose sum is σ = 56259288. Its totient is φ = 9376544.

The previous prime is 28129637. The next prime is 28129643. The reversal of 28129638 is 83692182.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

28129638 is an admirable number.

It is a super-2 number, since 2×28129638² = 1582553068022088, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 28129596 and 28129605.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28129631) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2344131 + ... + 2344142.

It is an arithmetic number, because the mean of its divisors is an integer number (7032411).

Almost surely, 2^28129638 is an apocalyptic number.

28129638 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

28129638 is a wasteful number, since it uses less digits than its factorization.

28129638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4688278.

The product of its digits is 41472, while the sum is 39.

The square root of 28129638 is about 5303.7381157067. The cubic root of 28129638 is about 304.1268154541.

The spelling of 28129638 in words is "twenty-eight million, one hundred twenty-nine thousand, six hundred thirty-eight".